Promotional Effect and Molecular Mechanism of Synthesized Zinc Oxide Nanocrystal on Zirconia Abutment Surface for Soft Tissue Sealing

Studies have confirmed that tooth loss is closely related to systemic diseases, such as obesity, diabetes, cardiovascular diseases, some types of tumors, and Alzheimer's disease. Among many methods for tooth restoration, implant restoration is the most commonly used method. After implantation, long-term stability of implants requires not only good bone bonding but also good soft tissue sealing between implants and surrounding soft tissues. The zirconia abutment is used in clinical implant restoration treatment, but due to the strong biological inertia of zirconia, it is difficult to form stable chemical or biological bonds with surrounding tissues. In this study, we investigated synthesized zinc oxide (ZnO) nanocrystal on the zirconia abutment surface by the hydrothermal method to make it more beneficial for soft tissue early sealing and the molecular mechanism. In vitro experiments found that different hydrothermal treatment temperatures affect the formation of ZnO crystals. The crystal diameter of ZnO changes from micron to nanometer at different temperatures, and the crystal morphology also changes. In vitro, scanning electron microscopy, energy dispersive spectrometry, and real-time polymerase chain reaction results show that ZnO nanocrystal can promote the attachment and proliferation of oral epithelial cells on the surface of zirconia by promoting the binding of laminin 332 and integrin β4, regulating the PI3K/AKT pathway. In vivo, ZnO nanocrystal ultimately promotes the formation of soft tissue seals. Collectively, ZnO nanocrystal can be synthesized on a zirconia surface by hydrothermal treatment. It can help to form a seal between the implant abutment and surrounding soft tissue. This method is beneficial to the long-term stability of the implant and also can be applied to other medical fields.